`
https://leetcode.cn/problems/bulb-switcher/
`

/**
 * @param {number} n
 * @return {number}
 */
var bulbSwitch = function (n) {
  // https://labuladong.online/algo/frequency-interview/one-line-solutions/#%E4%B8%89%E3%80%81%E7%94%B5%E7%81%AF%E5%BC%80%E5%85%B3%E9%97%AE%E9%A2%98
  return Math.floor(Math.sqrt(n))
};